made dnadb unsettable once set
made dnadb unsettable once set

mjg17/ensembl,Ensembl/ensembl,danstaines/ensembl,Ensembl/ensembl,muffato/ensembl,willmclaren/ensembl,james-monkeyshines/ensembl,james-monkeyshines/ensembl,danstaines/ensembl,mjg17/ensembl,at7/ensembl,at7/ensembl,danstaines/ensembl,Ensembl/ensembl,james-monkeyshines/ensembl,willmclaren/ensembl,muffato/ensembl,muffato/ensembl,muffato/ensembl,mjg17/ensembl,at7/ensembl,james-monkeyshines/ensembl,mjg17/ensembl,at7/ensembl,Ensembl/ensembl